Tip: 0.394 (10mm) in refers to the Diamond material portion, not the white portion. 【Lengthening Design】: Each diamond drill bits for ceramic adopting lengthened diamond sand, most of which are 0.35in in the market; the diamond sand of ZKH diamond drill is 0.394in, which makes the service life of the ceramic tile drill bits longer. 【8 Pcs Tile Drill Bits Set】: 2pcs 3/16"(5mm) , 2pcs 1/4"(6mm), 2pcs 5/16"(8mm), 1pcs 3/8"(10mm), 1pcs1/2"(12mm), diamond Ceramic drill bit can meet different drilling requirements. 【Dry Drilling Design】: Wax lubricant is integrated inside each diamond drill bit ; it melts and cools the tip of the porcelain drill bits, preventing diamond loss and allowing the diamond bits for drill to cool after each drill. 【Precise Design & Clean Drilling】:Round shank, compatible with most popular electric drills, angle grinders and bench drills; Special side cutting edge design for faster debris removal; Dry diamond core drill bit set with vacuum brazed diamond technology for clean holes in tile, porcelain, granite, ceramic. 【Easy to Carry and Use】: The tile drill bit comes with a separate storage case that prevents loss and prevents friction and wear between glass Drill Bit. It also makes the masonry drill bits easy to use and store. 8 Pcs Diamond Drill Bits Set Material: Diamond Size: 3/16" x 2pcs, 1/4" x 2pcs, 5/16" x 2pcs, 3/8", 1/2" Shank: Round For Material: Porcelain Ceramic Marble Stone Glass Granite